1. FIELD OF THE INVENTION
The present invention relates to double-acting shock absorbers and has specific reference to a double-acting shock absorber for throttling a fluid flowing through a narrow passage for damping out a movement.
This invention is applicable to various industrial fields in general, wherever it is required to damp out a movement of a part in relation to another part.
2. THE PRIOR ART
Conventional and hitherto known shock absorbers, notably those utilized on land vehicles, comprise as a rule a closed cylinder in which a piston is adapted to slide while throttling a fluid, this piston being connected to a rod extending through one of the cylinder ends. Thus, according to the particular configuration of the elements concerned, the piston rod and the cylinder of the shock absorber are rigidly connected the one to a fixed member and the other to a movable member, or vice versa. These shock absorbers operate on the principle of the inertia effect produced by a fluid flowing through a throttling or the like. In this case and for this purpose, the shock absorber comprises two chambers interconnected by a conduit of relatively reduced diameter, the piston movement causing the fluid to be transferred from one chamber to the other chamber. Many modified versions of the conventional configuration of shock absorbers of this type are known in the art, notably in connection with the chambers containing the fluid which, on the other hand, may be either liquid or gaseous. Thus, according to a modified form of embodiment, the piston divides the inner space of the cylinder into two chambers and comprises in addition one or two conduits for transferring the fluid between these chambers. In other known constructions the cylinder is double walled and contains a fluid which can flow through throttling passages from the external chamber to the central chamber.
With this specific configuration, this type of shock absorber is not suited for guiding the movement of a movable member in relation to a fixed member. As a rule, this guiding function is devolved to other means interconnecting said movable and fixed members.
It is also known to provide shock absorbers having a piston retained by two piston rods disposed in mutual axial alignment, each rod extending through one of the cylinder ends. Under these conditions, in many instances the ends of the two rods are rigidly connected to the fixed member, so that the movable member can be guided in relation to said fixed member via the cylinder. However, it is observed that this guiding action can only take place along particularly short bearing surfaces, notably in the piston cylinder fitting surfaces and in the orifices machined in the end plates of the cylinder and permitting the passage of the piston rods. Moreover, due to be necessity of obtaining a good fluid-tightness along each one of said bearing surfaces, the efforts exerted perpendicularly to the cylinders and piston rods must necessarily be kept within relatively low limits.